Automatic oil tester is designed as per the requirement of IEC156 Testing Method of Insulation Oil Medium Strength, which via proper programming, has got functions of auto boosting, step down, stirring, display and print out. After breakdown of oil medium, HV break off will operate within 10 seconds to enable an auto isolation of control system partly; This effectively safeguards the personnel security and equipment safety. The tester is suitable for testing of the strength of insulation oil medium, as well as for testing of withstand voltage of transformer oil.